Vacuum brake apparatus



Jan. 31, 1933. c. c. FARMER 1,895,456

VACUUM BRAKE APPARATUS Filed Feb. 15. 1928 INVENTOR CLYDE C. FARMERATTORNEY Patented Jan. 31 1933 UNITED STATES PATENT OFFICE CLYDE C.FARMER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE WESTINGHOUSE AIRBRAKE COMPANY, OF WILMERDING, PENNSYLVANIA, A CORPORATION OFPENNSYLVANIA VACUUM BRAKE APPARATUS Application filed February 15, 1928.Serial No. 254,416.

This invention relates to brakes, and more particularly to a motorvehicle brake adapted to be operated by the reduced pressure created inthe intake manifold of an internal combustion engine.

It has heretofore been proposed to operate a brake on a motor vehicle bymeans of the reduced pressure created in the intake manifold of aninternal combustion engine, in which the brake connection is madebetween the usual engine throttle and the'intake manifold.

With the above arrangement, ordinarily the throttle Will be in itsidling posit-ion, supplying a minimum flow of the motor fuel and airmixture, when the brakes are to be applied.

In applying the brakes, air from the brake cylinder flows to the intakemanifold and if the engine throttle is in or nearly in its idlingposition, then the additional air admitted to the manifold from thebrake cylinder will make the mixture of fuel and air so lean that theengine is liable to stall.

The principal object of my invention is to provide a brake apparatuswhich utilizes the vacuum created in the manifold for operating thebrake Without tending to cause the engine to stall when the brakes areapplied.

In order to accomplish this result, I eifect the desired reduction influid pressure in the brake cylinder by connecting the brake cylinderwith the air intake passage to the usual carburetor and I provide athrottle valve in the air intake passage for controlling theacceleration of the engine, dispensing with the usual throttle valvebetweenthecarburetor and the intake manifold of the engine.

In the accompanyingdrawing, the single figure is a diagrammatic view,partly in sec-.

tion of a motor vehicle brake apparatus embodying my invention.

In the drawing, the reference numeral -1 indicates an internalcombustion engine having an intake manifold 2. Attached to the intakepipe 3 is a carburetor having a needle valve 4 for controlling thesupply of motor fuel to the intake pipe, a float valve 5 operated by theusual float 6, and an air intake pipe 7. According to my invention, thethrottle valve in the intake pipe is dispensed with and a throttle valve8 is disposed in the air intake the application and releaseof the brakeson the vehicle.

The chamber at the right of the piston 11 is open to the atmospherethrough port 13 and the chamber at the left of the piston is connectedto pipe 9.

Interposed in pipe 9 is a brake controlling valve device 14 having avalve 15 operable by a handle 16 and provided with a three,

way passage 17 adapted in one position of the valve to connect the brakecylinder side of pipe 9 with an atmospheric port 18 and in anotherposition to establish communication from the brake cylinder 10 throughpipe 9 to the air intake pipe 7.

The fuel spray nozzle 19 supplies motor fuel to the intake pipe 3 inproportion to the rate of flow of air through passage 20 from the airintakepipe 7 and an auxiliary air passage 21 may be provided containingan auxiliary air valve 22 for admitting additionalair to the intake pipe3 when the engine suction increasesto a predetermined degree.

According to my invention, instead of having the pressure in the floatchamber 23 al- .24, comprising acasing 25 having a chamber 26 containinga-loose fitting piston 27 A valve 28 is carried by said piston andnormally the valve is held unseatedby the pressure of a spring 29 actingon the piston. When a back fire occurs, the sudden increase in pressurein pipe 7 acting through pipe 24: communication from the brake cylinderto on piston 27 acts to move the valve 28 to its the air intake pipe.

seat, thus preventing the flow of gas to the float chamber and thepossible ignition of the motor fuel therein.

In operation, if it is desired to apply the brakes, the handle 16 isoperated to shift the valve 15 to the position in which passage 17establishes communication from the brake cylinder 10 through pipe 9 tothe air intake pipe 7. The fluid pressure in the chamber at the left ofpiston 11 is thus reduced by flow to the intake manifold of the engineand the brakes are applied by the movement of piston 11 to the left bythe atmospheric pressure acting in the chamber at the right of thepiston.

Air passing from the brake cylinder to the air intake pipe 7 flowsthrough passage 20 with air flowing in the usual manner through the airintake pipe 7 and acts on the fuel spray nozzle 19 to induce a flow ofmotor fuel in proportion to the flow of air and an excessive flow ofmotor fuel is prevented since the pressure acting on the fuel in thefloat chamber 23 is maintained substantially equal to the pressure ofair flowing through pipe 7, by reason of the connection of the floatchamber, through pipe 24:, with the air intake pipe.

Since air from the brake cylinder is notintroduced into the manifoldbetween the carburetor and the manifold, the mixture of air and motorfuel is not so weakened as to cause the engine to stall.

While one illustrative embodiment of the invention has been described indetail, it is not my intention to limit its scope to that embodiment orotherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. The combination with the intake manifold of an internal combustionengine and a carburetor having an air intake pipe, of a throttle valvefor the engine located in the air intake pipe, a pressure elementoperable by the reduced pressure of air in said air intake pipe andconnected to the air intake pipe between said throttle valve and the carburetor, and means for controlling communication from said element tothe air intake pipe.

2. The combination with the intake manifold of an internal combustionengine and a carburetor having an air intake pipe, of a throttle valvefor the engine located in the air intake pipe, a brake cylinder having apiston operable by the reduced pressure of air in said air intake pipefor applying the brakes and connected to the air intake pipe betweensaid throttle and the carburetor, and a manually operated valve forcontrolling In testimony whereof I have hereunto set my hand.

